Product Description:

The 55NM81-200-2 is a permanent-magnet DC servomotor produced by Pacific Scientific within the Low Inertia PMDC Servomotors series. This motor is intended for industrial automation axes that demand quick acceleration and repeatable velocity control, such as material-handling gantries, light machine tools, and indexing conveyors. By combining low rotor inertia with an Alnico V magnet set, the unit supports rapid current-to-torque conversion while keeping weight and mechanical latency to a minimum. This layout is well suited to axes that reverse direction often, because the motor can respond quickly to changes in commanded speed and load.

The motor uses a medium torque-constant winding, and its electrical supply is rated for 48 V to match common low-voltage servo drives. Under that supply, the armature draws a continuous RMS current of 23.2 A and delivers a nominal speed of 1750 rpm. At that operating point, the shaft produces 472 oz-in of torque and a mechanical output of 611 W. When the shaft is locked, the motor can sustain a continuous stall torque of 504 oz-in while dissipating 500 W of heat through its Type 2 convection cooling path. Rotor inertia is limited to 0.010 oz-in-s², which helps the drive follow aggressive velocity profiles without excessive overshoot during rapid changes in speed.

The back electromotive force constant is 15.82 V/kRPM, and the torque constant is 21.4 oz-in/A for predictable drive response. Thermal management is aided by a resistance of 0.26 °C/W, which helps keep winding temperatures within safe margins during high-duty cycles. For short bursts, the armature can accept a pulse current of 54 A, enabling quick acceleration toward the no-load speed of 2965 rpm. That short-term current capacity helps the motor recover from sudden load changes while supporting fast starts and rapid speed corrections.